1. Field of the Invention:
The present invention relates to a process for producing a metallic magnetic powder by adsorbing zinc ion Zn.sup.2+ on iron oxyhydroxide and then reducing it in hydrogen gas atmosphere etc. to form fine metallic powder.
2. Description of Prior Arts:
Heretofore, acicular iron oxide has been mainly employed as a magnetic powder for magnetic recording media.
In view of the recent development and widespread use of magnetic recording apparatus such as home VTR and high functional audio cassettes, it has been required to attain high density recording of signal for a magnetic recording medium. It has been difficult to attain such requirement for high density magnetic recording only by using the acicular iron oxide. It has been required to obtain a magnetic powder having higher coercive force and higher magnetic flux density. Recently, fine metallic powders have been studied as magnetic powders having such required magnetic characteristics. In view of increase of utility of the magnetic powder for short wavelength recording, a fine metallic powder having further superior magnetic characteristics has been needed.
It has been known to produce a fine metallic powder by reducing iron oxyhydroxide at 350.degree. to 500.degree. C. in hydrogen gas flow as one process.
Various processes have been proposed to improve the magnetic characteristics, for example, a formation of iron oxyhydroxide having superior squareness, an addition of a third component such as Co, Ni, Sn and Al in the production of iron oxyhydroxide, an adsorption of the third component on iron oxyhydroxide, or an adsorption of a sintering inhibitor on iron oxyhydroxide.